1. Field of the Invention
This invention relates to a binocular stereomicroscope for use as a microscope for surgical operations, or the like.
2. Description of the Prior Art
For example, when surgical operations are carried out on minute diseased parts, enlarged images of the diseased parts have heretofore been formed with binocular stereomicroscopes, and the diseased parts have heretofore been treated by seeing the enlarged images. Such a binocular stereomicroscope comprises an objective lens and a magnifying optical system, which substantially constitutes a binocular magnifier and which is located at the rear of the objective lens. In order to adjust the focusing point of the binocular stereomicroscope, a mechanism provided with a rack and pinion, which is formed on a stay and which vertically or horizontally moves the whole binocular stereomicroscope, has been put into practice.
Also, a binocular stereomicroscope has heretofore been known which is provided with an illumination means for illuminating an object. The illumination means is constituted such that a light beam produced by a light source may pass through an objective lens and may then impinge upon the object.
However, in cases where the mechanism is employed which carries out the focusing operation by moving the whole binocular stereomicroscope such that the position of the object may coincide with the position of the focal length of the objective lens, it becomes necessary to provide a considerably large-scaled structure in order to move the heavy mass and then keep it stationary at an arbitrary position. Also, a special member or mechanism is often required to fix the heavy mass at an arbitrary position.
As a result, the whole binocular stereomicroscope, including the focusing mechanism, becomes large in size and heavy in weight. Therefore, the focusing operation and movement of the binocular stereomicroscope cannot be carried out smoothly. Also, the cost of the binocular stereomicroscope cannot be kept low. In particular, in cases where the binocular stereomicroscope is used for a surgical operation and a state of emergency, e.g., bleeding, occurs during the surgical operation, the binocular stereomicroscope must be removed from the object, and an urgent treatment must be carried out on the object. When the surgical operation is again carried out on the object, it is necessary to carry out a re-focusing operation. Thus, movement and the focusing operation of the binocular stereomicroscope must be carried out in addition to the treatment on the diseased part. Therefore, there is the risk that the surgical operation cannot be carried out quickly.
A binocular stereomicroscope may be constituted such that the focusing operation may be carried out automatically in accordance with a signal obtained from a distance measuring means. However, in such cases, if the focusing operation is carried out by moving the heavy part, a large focusing mechanism is required. Therefore, smooth, quick, and accurate operations cannot be carried out.
Moreover, with the conventional binocular stereomicroscope, its eyepieces move during the focusing operation. Therefore, in order to observe a good microscope image, the positions of the eyes of the operator must be shifted in accordance with the focusing operation. Also, it will often occur that parts of the eyepieces strike against the eyes of the operator during the focusing operation. Thus a need exists for an improvement in the operability and image observation characteristics.